Role of sliding block rotation on earthquake-induced permanent displacement of earth slopes

Abstract

Different methods are available for estimating earthquake-induced permanent deformation of earth slopes and embankments. Due to its simplicity, Newmarkian rigid block analogy has received considerable attention among the geotechnical practitioners and researchers. Since the conventional Newmarkian analogy has considered many limiting assumptions, conservative and unconservative estimate of sliding displacement would be possible. Thus, researchers have proposed many modifications to enhance the realistic features of this method. In reality, it is anticipated that the downward rotational (stabilizing) movement of the soil mass can significantly affect the yielding acceleration of the presumed slip surface. In this paper, the mentioned modification is numerically implemented to the conventional formulation of the Newmark approach for actual earthquake excitations. The results are presented for several conditions including the conventional rigid block, decoupled assumption of sliding and slope response, coupled consideration of sliding and slope response, and decoupled assumption with the effect of sliding block rotation. According to the results of this study, the period ratio (the ratio of natural period of slope to the mean period of input motion) and the length of slip surface can significantly vary the permanent displacement of sliding mass for these conditions.